Prevent large Gemini payloads from being duplicated during normalization

Use no-copy contents views and lock the 20 MiB inline-data paths with allocation coverage.

Constraint: Translator-only changes require repository write access; verified against the websprit fork with a successful push dry-run.
Rejected: Streaming translator output | exceeds the two requested P0 fixes.
Confidence: high
Scope-risk: narrow
Directive: Keep no-copy GJSON results scoped to the lifetime of their immutable input bytes.
Tested: go test ./...; go build ./cmd/server; targeted go vet; 20 MiB inlineData allocation tests and benchmarks.
Not-tested: Full-repository go vet remains blocked by pre-existing logging and pluginhost findings.